1. Technical Field
This invention relates in general to data access and storage devices, and in particular to modular disk drives. Still more particularly, the present invention relates to an array of disk drives that are removable from a backplane, wherein each of the disk drives contains separate mechanical components and the backplane contains an integrated array of electrical components corresponding to the mechanical components.
2. Description of the Related Art
Generally, a data access and storage system consists of one or more storage devices that store data on magnetic or optical storage media. For example, a magnetic storage device is known as a direct access storage device (DASD) or a hard disk drive (HDD) and includes one or more disks and a disk controller to manage local operations concerning the disks. The hard disks themselves are usually made of aluminum alloy or a mixture of glass and ceramic, and are covered with a magnetic coating. Typically, two or three disks are stacked vertically on a common spindle that is turned by a disk drive motor at several thousand revolutions per minute (rpm).
A typical HDD also has a movable head stack assembly. Within most HDDs, one magnetic read/write head or slider is associated with each side of each platter and hydrodynamically flies just above the platter""s surface. Each read/write head is mounted on a flexible suspension to form a head gimbal assembly (HGA). The HGA is then attached to a semi-rigid arm apparatus that supports the entire head flying unit. Several semi-rigid arms may be combined to form a single armature unit.
Each read/write head scans the surface of a disk during a xe2x80x9creadxe2x80x9d or xe2x80x9cwritexe2x80x9d operation. The head and arm assembly is moved utilizing an actuator that is often a voice coil motor (VCM). The stator of a VCM is mounted to a base plate or casting on which the spindle is also mounted. When current is fed to the motor, the VCM develops force or torque that is substantially proportional to the applied current. The arm acceleration is therefore substantially proportional to the magnitude of the current. As the read/write head approaches a desired track, a reverse polarity signal is applied to the actuator, causing the signal to act as a brake, and ideally causing the read/write head to stop directly over the desired track.
For example, an information storage system comprising a magnetic hard disk file or drive 11 for a computer system is shown in FIG. 1. Drive 11 has an outer housing or base 13 containing a plurality of stacked, parallel magnetic disks 15 (one shown) which are closely spaced apart. Disks 15 are rotated by a spindle motor located therebelow about a central drive hub 17. An actuator 21 comprises a plurality of stacked, parallel actuator arms 25 (one shown) in the form of a comb that is pivotally mounted to base 13 about a pivot assembly 23. A controller 19 is also mounted to base 13 for selectively moving the comb of arms 25 relative to disks 15.
In the embodiment shown, each arm 25 typically has extending from it a pair of parallel, cantilevered load beams or suspensions 27, and a head 29 having at least one magnetic read/write head secured to each suspension 27 for magnetically reading data from or magnetically writing data to disks 15. The level of integration called head gimbal assembly is head 29 mounted on suspension 27. Suspensions 27 have a spring-like quality which biases or maintains them in parallel relationship relative to one another. A motor voice coil 31 housed within a conventional voice coil motor magnet assembly (not shown) is also mounted to the comb of arms 25 opposite heads 29. Movement of an actuator driver 33 (indicated by arrow 35) moves heads 29 in an arc across tracks on the disks 15 until the heads 29 settle on the target track. The heads 29 operate in a conventional manner and always move in unison with one another, unless drive 11 uses a split actuator (not shown) wherein the arms move independently of one another.
The individual hard disk drives in, for example, a redundant array of independent drives (RAID) typically receive power through a hard-wired connector interface with a backplane. Each of the drives is loaded in a drive carrier, mounted in a drawer in the storage subsystem, and individually connected in parallel to the backplane. Each drive also has a read/write interface, such as a conventional small computer system interface (SCSI) or Fibre Channel Arbitrated Loop (FC-AL) connector, that allows the host computer to access and store data on the disk drive. All of these elements are combined into an integrated unit that must be serviced as a single entity. Although current hardware designs are acceptable, an improved and more efficient apparatus and method for performing maintenance on the individual disk drives would be desirable.
In one embodiment of a disk drive of the present invention, the drive is provided with discrete, modular mechanical and electrical devices. The mechanical device includes a casing to which is mounted a drive motor, disks, and an actuator that is driven by a voice coil motor. The actuator supports transducers for interacting with the disks. The electrical device is attached to a backplane and provides various control and data communication functions for the mechanical device with a host computer. In addition, each of the mechanical and electrical components has a mating connector for detachably interfacing with each other.
The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the preferred embodiment of the present invention, taken in conjunction with the appended claims and the accompanying drawings.